You should not expect online lessons to be the same as face-to-face lessons. In our school we used to offer Skype lessons, which were only partially successful. If the focus of the lessons is more on technical issues, like grammar or writing style questions, and the learner takes a proactive attitude, online teaching is effective. However, if your primary goal is to develop your conversation skills by interacting with a native speaker, connecting on a personal level, Skype is a poor replacement for the live contact.